Thursday, October 28, 2010

North Easterly winds are 'RINISING' south eastern coast of India especially Tamilnadu. The SWM 2010 withdrawal is evident by widespread TS activity in Tamilnadu. Usually withdrawal will be pronounced in coastal areas, where as during this SWM 2010 withdrawal period interior and western parts of TN is experiencing more TS activity than the coastal area.

My immediate boss pointed out a peculiar scenario in which it is noted that western Pacific High Pressure system located in China, is drifting towards WEST.

This upper winds drag clouds along its path.

Further the resultant reaction between receding westerlies and the meso scale incoming easterlies cause horizontal vortex to form and resulted in TS in interior to western parts of TN.

It is interpreted from model OUTPUTS that in the entire troposphere, easterlies will be strengthening within next 36 hrs to proclaim the onset of NEM 2010.

The loose spiraling clouds of Typhoon Chaba are spread across most of the Philippine Sea in this true-color image from October 27, 2010. When the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired the image at 10:25 a.m. local time (2:25 UTC), Chaba was strengthening into a Category 3 storm. Two hours earlier, the Joint Typhoon Warning Center estimated Chaba’s winds to be 95 knots (176 kilometers per hour or 109 miles per hour), and the storm reached 100 knots (185 km/hr or 115 mph) by 2:00 p.m. local time. Chaba was forecast to weaken into a tropical storm before going ashore over Japan on about October 30.
The large image is the highest-resolution version of the image. The image is available in additional resolutions from the MODIS Rapid Response Team.

An intense high-pressure area (anticyclone) has dug in deep over South-East Asia compressing the north-easterly flows along its southern flank into an intensive band as they head for the Andaman Sea.

In fact, the Thai Met Department has spoken about a strengthening North-East monsoon current across southern Thailand and the upper Gulf of Thailand over the next five days.

MONSOON TROUGH

The area of northeast monsoon influence is joined to the immediate west with the monsoon trough over the Andaman Sea, which would bring heavy to very heavy falls over these regions.

This is exactly the timeline within which India Meteorological Department (IMD) expects the northeast monsoon to unveil along the Tamil Nadu coast.

It has maintained the watch for commencement of northeast monsoon rains over Tamil Nadu and adjoining Peninsular India around Friday.

The European Centre for Medium-Range Weather Forecasts (ECMWF) has retained the watch for weak low-pressure area washing over along the North Tamil Nadu coast to scale up rainfall.

‘LOW' NEXT WEEK

A full-fledged ‘low' has been forecast by Tuesday (Nov 5), which some models suggest could intensify over East-central Bay of Bengal.

There is, however, no consensus on the track it might take, since a progressively activating East Indian Ocean could force the system to digress from its path and head south-southeast and away from Tamil Nadu coast.

In any case, fairly widespread rain or thundershowers has been forecast over Tamil Nadu, Coastal Andhra Pradesh, Kerala and Andaman and Nicobar Islands during the weekend.

It would be scattered over Rayalaseema, South Karnataka and Lakshadweep.

Meanwhile, Peninsular India has been witnessing some heralding weather already, with fairly widespread rain being reported from Coastal Karnataka during the 24 hours ending Wednesday morning.

It was scattered over Tamil Nadu, South Interior Karnataka and the Andaman and Nicobar Islands while being isolated over Coastal Andhra Pradesh and Kerala.

The ruling weather system continued to be the upper air cyclonic circulation over West-central Bay of Bengal, generating cloudiness over the region.

An Insat cloud imagery in the afternoon showed the presence of convective (rain-producing) clouds over parts of South Bay of Bengal, Andaman Sea, Southeast Arabian Sea, South Coastal Andhra Pradesh, South Karnataka and North Kerala.